Some Developments of the Cooray–Rubinstein Formula in the Time Domain

A rigorous formula representing the counterpart of the Cooray-Rubinstein expression in the time domain has recently been derived by the authors. In this paper, the formula is particularized for the cases of a unit step and a linearly rising channel-base current, waveforms frequently used in lightning performance studies. Furthermore, an approximate kernel of the formula is also presented, allowing a very compact and straightforward solution for the case of linearly rising currents.